1. Field of the Invention
Embodiments of the invention relate to a system and a method for evaluating a crosstalk of a stereoscopic image display.
2. Discussion of the Related Art
A stereoscopic image display is classified into a display using a stereoscopic technique and a display using an autostereoscopic technique.
The stereoscopic technique, which uses a parallax image between left and right eyes of a user with a high stereoscopic effect, includes a glasses type method and a non-glasses type method. In the glasses type method, the parallax image between the left and right eyes is displayed on a direct-view display or a projector through a change in a polarization direction of the left and right parallax image or in a time-division manner, and thus a stereoscopic image is implemented using polarization glasses or shutter glasses. In the non-glasses type method, an optical axis of the parallax image between the left and right eyes is separated generally using an optical plate such as a parallax barrier and a lenticular lens, and thus the stereoscopic image is implemented.
A glasses type stereoscopic image display generally displays a left eye image and a right eye image on a display panel in a time division manner. Glasses the user wears include a left eye filter (or a left eye shutter) for transmitting light of the left eye image and a right eye filter (or a right eye shutter) for transmitting light of the right eye image. Thus, the user may view only the left eye image during odd-numbered frame periods and may view only the right eye image during even-numbered frame periods, thereby feeling a stereoscopic feeling through the stereoscopic technique.
The user, that views a stereoscopic image through the glasses type stereoscopic image display, may perceive a 3D crosstalk, in which the user views doubled image by leaking part of the left eye image into the right eye image and vice versa. There is a ghosting phenomenon as an example of the 3D crosstalk. In the ghosting phenomenon, because a gray level of a current left eye image or a current right eye image is affected by a gray level of a previous left eye image or a previous right eye image that has been previously displayed on the display panel, the current left/right eye image is reproduced at a gray level different from an original gray level of the current left/right eye image.
The 3D crosstalk is generally generated because a gray level of one (for example, a left eye image) of left and right eye images is affected by a gray level of the other image (for example, the right eye image) and is reproduced at a gray level different from an original gray level of the one image. The existing method for evaluating the 3D crosstalk was implemented by quantifying the ghosting phenomenon. For this, the stereoscopic image display alternately displayed the left and right eye images each having a black gray level and a white gray level, and luminances of the left and right eye images passing through the left eye filter and the right eye filter of the glasses were measured by a luminance meter. The 3D crosstalk was evaluated using an algorithm for measuring an increasing level of the back gray level of the left eye image affected by the white gray level of the right eye image based on the luminance of the left eye image measured by the luminance meter and an algorithm for measuring an increasing level of the back gray level of the right eye image affected by the white gray level of the left eye image based on the luminance of the right eye image measured by the luminance meter.
In the method for evaluating the 3D crosstalk, the crosstalk evaluation algorism of the left eye image is expressed by the following Equation (1):
                              CTL                      B            ,            W                          =                                                            L                BW                            -                              L                BB                                                                    L                WB                            -                              L                BB                                              ×                      100            ⁡                          [              %              ]                                                          (        1        )            
where CTLB,W is the 3D crosstalk at the black gray level of the left eye image affected by the white gray level of the right eye image, LBW is a luminance when the black gray level of the left eye image is greater than a desired black gray level because of an influence of the white gray level of the right eye image, and LWB is a luminance when the white gray level of the left eye image is less than a desired white gray level because of an influence of the black gray level of the right eye image.
Further, in the method for evaluating the 3D crosstalk, the crosstalk evaluation algorism of the right eye image is expressed by the following Equation (2):
                              CTR                      B            ,            W                          =                                                            R                BW                            -                              R                BB                                                                    R                WB                            -                              R                BB                                              ×                      100            ⁡                          [              %              ]                                                          (        2        )            
where CTRB,W is the 3D crosstalk at the black gray level of the right eye image affected by the white gray level of the left eye image, RBW is a luminance when the black gray level of the right eye image is greater than a desired black gray level because of an influence of the white gray level of the left eye image, and RWB is a luminance when the white gray level of the right eye image is less than a desired white gray level because of an influence of the black gray level of the left eye image.
In the existing method for evaluating the 3D crosstalk, the 3D crosstalk between the left and right eye images each having only the white gray level and the black gray level was evaluated, and the 3D crosstalk between the left and right eye images having other gray levels was evaluated using an approximation method. However, the stereoscopic image display displays not only images having the white gray level and the black gray level but also images having 2n gray levels, where n is a bitrate of pixel data of an input image. Thus, because the existing method for evaluating the 3D crosstalk does not consider the real use environments of the stereoscopic image display, the 3D crosstalk at each of all of representable gray levels of the stereoscopic image display cannot be accurately evaluated.